Approaches to Mitigate Edge Recombination Effects in Silicon Lifetime Samples With Emitter

Abstract

Insufficiently sized symmetric lifetime samples with pn-junction exhibit a specific injection-dependent effective charge carrier lifetime measured by photoconductance decay due to increased edge recombination, characterized by a strong decline toward low injection. In this study, various approaches are presented to suppress these edge effects in n-type Si samples with boron emitter. These approaches include edge passivation using AlO$_{\text{x}}$ from atomic layer deposition and the creation of an undiffused buffer layer between the central measurement area and recombination-active edges. For the latter, both an etch-back approach and a masked diffusion of the boron emitter (sunken emitter) are evaluated. Lifetime measurements and photoluminescence imaging demonstrate that the sunken emitter approach most effectively suppresses edge recombination in small-sized lifetime samples.